/Engine/Source/Runtime/MeshConversion/Public/DynamicMeshToMeshDescription.h
Use the MeshIn Overlays to update the Tangent and BinormalSign attributes of the MeshDescription, assuming mesh topology has not changed. Does not modify any other attributes. NOTE: assumes the order of triangles in the MeshIn correspond to the ordering you'd get by iterating over triangles, on MeshOut This matches conversion currently used in MeshDescriptionToDynamicMesh.cpp, but if that changes we will need to change this function to match!
void UpdateTangents ( const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) * MeshIn, [FMeshDescription](API\Runtime\MeshDescription\FMeshDescription) & MeshOut )